Roof installations

ABSTRACT

Roof installations consisting of an array of interfitting members e.g. tiles, strips (3), slats or the like which interfit to form a roof covering and a set of heat pipes (7) which run parallel to the plane of the roof (6,1). Heat is abstracted from the heat pipes and used directly or indirectly, e.g. via a heat pump apparatus. Solar energy may thus be captured, as well as ambient energy, e.g. arising from the building below.

This invention relates to roof installations, particularly adapted tocollecting solar energy.

For some years attempts have been made to make use of the energy fallingon roofs from solar radiation. The classical approach has been to mountso-called solar panels on the roof, these generally consisting of someform of sandwich or tubular construction through which a working fluid,usually water, was passed, the construction being designed to be heatabsorbing e.g. by being matte black. Such systems are expensive in termsof capital cost, prone to difficulties of sealing, corrosion andclogging in use, and tend not to blend aesthetically with the roofstructure. Although they allow impinging radiant energy to be used,conversion efficiencies are very low.

Some devices of this type attempt to rely on the so-called greenhouseeffect of a trapped body of circulating air. Such types are particularlyprone to severe difficulties in operation due to condensation of trappedwater vapour.

Typical complex constructions of this nature are described in U.S. Pat.Nos. 4,133,298 and 4,479,487 and in various citations listed in each ofthose two specifications.

Reliance upon heat absorption and thermal conductivity to secureadequate heat transfer is not universal. Proposals have been made totake advantage of the improved heat transfer properties of so-calledheat pipes, closed systems in which a working fluid, for example afreon, is evaporated in one region of the pipe and condensed, giving upits latent heat of evaporation, in another region. U.S. Pat. Nos.3,996,919, 4,067,315 and 4,122,356 show a number of ways in which heatpipes have been proposed for use in connection with the collection anduse of solar energy.

None of the systems described in any of the specifications listed aboveis simple and straightforward to construct, nor is it particularlyefficient in use. In particular, none of the systems attempts tointegrate the collection of thermal solar energy with the constructionof a sound weather-proof roof structure.

In accordance with the present invention, an array of heat pipes is usedwhich is incorporated within a roof structure and in which the pipes runparallel to the plane of the roof structure.

Thus in accordance with a first feature of the present invention thereis provided a roof installation comprising a set of interfitting membersadapted to form a generally planar roof covering, a set of heat pipesconsisting of closed tubes each containing a quantity of evaporatableliquid, the axes of the pipes running parallel to the plane of the roofcovering, the pipes being in thermal contact with the interfittingmembers, and means for extracting heat from the heat pipes.

Such a system may be built into a flat roof but is preferably used in apitched roof, the upper ends of a set of heat pipes being locatedadjacent the ridge of the roof. However, although that system workswell, it is not necessary to run the heat pipes up and down the roof;they can run horizontally, either in a pitched roof or a flat one. Heatmay be extracted from the upper end of non-horizontal heat pipes or fromone or more positions in the case of horizontal heat pipes.

Heat pipes running generally parallel to the roof plane may beincorporated in a roof structure in a very wide variety of ways. One wayof particular value is to locate each of the heat pipes in a tubularhousing, either in one of the interfitting members of formed e.g. by twosemi-cylindrical grooves in adjacent interfitting members. In suchcases, the interfitting members are usually fairly long and e.g. in apitched roof run from eaves to ridge. An alternative approach is toprovide that each of the heat pipes is located in a set of alignedtubular housings in a corresponding set of interfitting members. Forexample a number of "tiles" may be threaded onto a heat pipe runningfrom eaves to roof ridge, either directly or they may be threaded onto atube which in turn contains a heat pipe.

The construction of the interfitting members must of course act as aroof i.e. it must keep out the weather and desirably look reasonable asa roof. In this connection, sets of tile members threaded on heat pipesor tubes may be employed to produce roofs looking very similar totraditional tiled roofs. Alternatively, longer sections may be used,e.g. running from eaves to ridge, and each containing a heat pipe. Insuch a case, each member may be in the form of a continuous pantilevisually unbroken, or the surface may be configured to make it look likea set of separate items, simulating a tiled roof.

In roof installations in accordance with the present invention, heat isabstracted from the heat pipes by any convenient means. For example theends of a set of heat pipes adjacent the ridge of a pitched roof may allterminate within a manifold through which a suitable liquid, e.g. awater/glycol mix, is circulated. As the liquid circulates it will removeheat from the end of each of the heat pipes. The heated circulatingliquid may be used as a working fluid, e.g. in radiators, or it may beused indirectly to heat other water, e.g. for washing in, or it may flowthrough a circuit forming part of a heat pump installation of knowntype. Heat pump installations of various types are known and these mayall be used in conjunction with installations according to the presentinvention. They are of considerable value in certain situations as theyallow operation at below ambient air temperature thus enabling usefulheat to be extracted from a roof even on cold days.

Heat transfer between the heat pipe and the set of interfitting membersof planar roof covering may be enhanced e.g. by a suitably thermallyconductive medium surrounding the heat pipe. Semi-liquid materials, e.g.as used to assist heat conduction in electronic environments, areusable.

The heat pipes themselves may be made of any convenient material.Preferred are tubes formed of aluminum or copper and including a workingfluid such as a freon or water.

The interfitting members may be made of a wide variety of materials, andin a wide variety of shapes and sizes. One approach is to usetraditional materials such as clay or concrete tiles and provide themwith apertures through which the heat pipes or a tube to receive themmay pass. The apertures are usually for convenience cylindrical thoughthey need not be so. Alternatively the interfitting members may be madeof suitable metal, for example fabricated metal sheet or extruded metalsection. Extruded sections are of particular importance as they can beproduced in substantial quantities once the extrusion dies have beenmanufactured. A further possibility is plastics units, e.g. made ofpolyester methyl methacrylate resins. The members may abut, overlap orbe keyed together, and other configurations are possible. The membersmay be sealed or welded together, or adhered by suitable means. One roofmay use more than one type of member.

Metal or plastics members may be finished e.g. with texturing, markings,contouring or the like to simulate, when assembled, the appearance of atraditional roof, e.g. a tiled or slated roof.

The invention is illustrated by way of example with reference to theaccompanying drawings in which:

FIG. 1 is a diagrammatic illustration of a roof installation inaccording with the present invention,

FIG. 2 is an alternative diagrammatic installation, and

FIGS. 3, 3A, 4 and 5 show yet further alternatives.

Referring to FIG. 1, this shows diagrammatically a section of a roofconstruction. The roof is a conventional timber-framed pitch roof whichconsists of inclined rafters 6 running from the eaves to the ridgeacross which a plurality of horizontal battens 1 are fixed, the battens1 normally being designed to hold tiles hung thereon.

In accordance with the invention, the roof cladding consists not oftiles but of a plurality of extruded metal sections 3 each running fromthe eaves of the building to the ridge of the roof. The central part ofeach extrusion consists of a generally hollow cylindrical section inwhich a heat pipe 7 is located. Adjacent sections 3 meet at 4 and areheld relative to one another by clips 8, but there need be no attempt toseal two adjacent sections together where they meet at 4. Instead thereare provided, likewise running from eaves to ridge, a set of verticallyrunning inclined gutters 5, adapted to catch both leakage from withoutand condensation within. Each member 3 is held in position by a springclip 2 mounted fixedly on top of the rafters 6 and battens 1. The widecollecting area of member 3 acts either to collect solar heat or heatfrom the building below and this is conducted to heat pipe 7. Heat isabstracted from the top end of the heat pipe which is located in amanifold through which a suitable liquid, e.g. glycol, is circulated toabstract the heat.

Referring now to FIG. 2, this shows an alternative arrangement in whichthe individual extruded sections run horizontally across a pitched roofrather than vertically up and down it. Each is held in place in a springchair 12 each of which is directly fixed to the rafters 16 with theinterposition of a damp-proof membrane or underslating 14 which isdesigned to protect the rafters 16 from the adverse effects ofcondensation. Again, heat may be extracted from members 13 by the use ofheat pipes which fit into the central section of the member 13.

FIG. 3 shows a further alternative version in which a plurality ofadjacent roof members 23 are assembled with heat pipes 24 between them.Members 23 are fabricated by cold rolling and each has on both its outeredges a semi-cylindrical groove such that two members 23, when placedadjacent one another define a cylindrical housing into which a heat pipe24 may be inserted, either directly or in a sleeve.

The mating edges of members 23 are held together by clips 26 and in turnheld into gutters 27 by spring clips 29 as shown. FIG. 3 includesperspective views of clips 26 and 29.

FIG. 4 shows a system analogous to FIG. 3 but with a pantile effect withasymmetric members 33. Clips 36 and 39 are analogous to clips 26 and 29.

FIG. 5 shows a simple version of the embodiment of FIG. 1 using pressedmetal sections 43 set on spring clips 42 attached to battens 41 onjoists 46. Drainage channels for rain water and condensation areprovided at 45.

Thermal transfer between heat pipe and the remainder of the installationmay be enhanced by ensuring that there is good thermal contact betweenthem, either physically or via a suitable heat conductive lubricant, forexample a mixture of an oil and zinc oxide.

The cross-section of the tubes may be circular, square, rectangular,oval, polygonal or other appropriate shape. The heat pipes may ifdesired be finned or otherwise treated to improve heat transfer.

What is claimed is:
 1. A roof installation for a pitched roofcomprising:a set of roof support members; a set of interfitting roofmembers with a curved underside and having peripheral edges lying insubstantively the same plane and adjacent to one another arranged toform a roof covering thereover and defining a roof space therebetween; aset of heat pipes positioned in the roof space and arranged to extendsubstantially from the ridge to eaves of the roof, each pipe consistingof a closed tube containing a quantity of evaporatable liquid and beingin thermal contact with the roof covering substantially along its entirelength; a plurality of channel members mounted in the roof space andpositioned below the peripheral edges of the panels, wherein the channelmembers are operable to collect rain entering the space and condensationformed in the space; and support means mounted on the roof supportmembers and operable to support the interfitting roof members at thelocations of the heat pipes.
 2. A roof installation according to claim1, wherein the interfitting roof members are formed by extrusion, andthe heat pipes are mounted within channels formed in the extrudedmembers.
 3. A roof installation according to claim 2, wherein thechannels are tubular and are formed along the centre of each extrudedmember, each member having an associated heat pipe.
 4. A roofinstallation according to claim 2, wherein the channels are formed atthe edges of the extruded member whereby the edges of two edges of theadjacent members define a tubular housing for a heat pipe.
 5. A roofinstallation according to claim 1, wherein the interfitting roof membersare shaped to improve the collection of condensation, the channelmembers being positioned in the roof space accordingly.
 6. A roofinstallation according to claim 5, wherein the interfitting roof memberhave a substantially arched crosssection, the channel members beingpositioned adjacent the lowest point of the arch.
 7. A roof installationaccording to claim 1, wherein heat is extracted from the heat pipes atthe ridge end of each pipe.